Swift/XRT observations of RX J0218.7+3854
ATel #16950; Amar Deo Chandra (Aryabhatta Research Institute of Observational Sciences (ARIES))
on 15 Dec 2024; 08:25 UT
Credential Certification: Amar Deo Chandra (amar.deo.chandra@gmail.com)
Subjects: X-ray, Transient
The X-ray transient RX J0218.7+3854 was detected on December 7, 2024 at 14:34:29 UTC by the Follow-up X-ray Telescope (FXT) onboard the Einstein Probe (ATel #16937). The location of the source was inferred to be R.A.=34.6990 deg, DEC=38.9136 deg (J2000) having an uncertainty of 10 arcsec (90% C.L., ATel #16937). Swift/XRT ToO observations of the source were carried out for about 2.1 ks in the Photon Counting (PC) mode on December 14, 2024 beginning at 05:51:02 UTC. We detected an X-ray source at the location RA/Dec(J2000)=34.699, 38.914 which is equivalent to:
RA(J2000) = 02h 18m 47.94s, Dec(J2000) = +38d 54m 51.8s,
with an error radius of 4.7 arc-seconds (90% confidence). The location of this source is consistent with the reported location of RX J0218.7+3854. The estimated average count rate during this observation was about 0.026+/-0.004 cts/s in the 0.3-10 keV energy band. From a preliminary analysis, the PC mode spectrum is well described by an absorbed power-law with photon index = 2.8 +/- 0.6, with absorption N_H = 5.92 +/- 0.4 x 10^20 cm^-2. The estimated unabsorbed flux in the 0.3-10 keV band is 9.4(+1.6-3.7) x 10^-13 erg/s/cm^2. Swift/XRT follow-up observations confirm X-ray brightening of the transient RX J0218.7+3854.
Follow-up multi-wavelength observations are encouraged. We thank the Swift Team and Observatory Duty Scientists who made these observations possible.
